Emergency driving device for motor vehicles

ABSTRACT

The invention concerns and emergency driving device ( 1 ) for motor vehicles with an automatic shift transmission, which has integrated in said transmission an electronic control unit ( 2 ), which, via at least one CAN-bus ( 7, 8 ) is connected with further electronic control units ( 3, 4, 5, 6 ) with which the control unit ( 2 ) exchanges measurement and regulation data. It is proposed, that the electronic transmission control unit ( 2 ) be connected to an auxiliary electronic service panel ( 13 ). Thereby, upon a fault of a CAN-bus organ interface thereof, the transmission can be shifted through all gear ratio stages.

FIELD OF THE INVENTION

The invention concerns an emergency driving device for motor vehicles.

BACKGROUND OF THE INVENTION

Automatically shifting transmissions are being installed in motorvehicles to an ever increasing extent. Such transmissions includetransmissions with stepless, changeable gear ratios, or transmissionwith stages, which shift under load or shift with interruption oftraction. An electronic control unit is assigned to such transmissions,which chooses and activates an appropriate gear change. This choice ismade with dependency on parameters of available power, driving mode, andtransmission characteristics. Additionally, the driver can optionallychoose one ratio change or a group of ratio changes by the use of aselector lever and/or a program switch.

The control and regulation of the transmission is dependent on and isinfluenced by the control of additional systems of the vehicle, namelyan engine, a service brake or a retarder brake system. These systemspossess, as a rule, their own electronic control units, which units, bymeans of data busses, communicate with one another and with theelectronic transmission control unit. The interconnection of such databusses is designated a Controller Area Network (hereinafter called “CAN”busses).

In case the transmission control drops out, because of a defect in theelectronics, as a rule, emergency devices are provided with which itbecomes possible to drive the vehicle away from the roadway with alimited operational capability, or even to drive the vehicle to the nextrepair station. Such an defect can, among other things, occur in thefailure of a CAN-bus or its interface.

EP 0 431 538 B1 discloses an emergency device, by which, in case offailure, a certain specified ratio stage can be brought into action bymeans of a special solenoid valve. The valve is activated manually bymeans of a screw, whereby certain logical circuitry of the normaltransmission in the central control unit is deactivated during theemergency switching.

EP 0 380 214 A2 makes known an additional emergency driving apparatus,which gives the driver the ability, if the usual electronic controlunit, or the distribution cable has faulted, thus bringing about a caseof emergency, to select a forward or a reverse direction gear ratio fromthe normally available gear ratios. The presupposition in this case, is,of course, that the shifting actuator can still function.

The road load, in the case of the known emergency driving devices, isvery limited, since for the forward and reverse movement, respectively,only one gear is available, and the shift must be into this, as a rulein a stillstand of the vehicle.

Thus the purpose of the invention, is to enable driving to be continuedand allowing shifting into a multiplicity of gears upon faulting of aCAN-bus or its corresponding interface.

SUMMARY OF THE INVENTION

In accord with the invention, the transmission control unit is connectedto a service panel. In case of a defect in the selector lever, or itssignal lines to the electronic control unit, such as the connections andCAN-bus, the control of the transmission can be carried out manually onthe service panel. If the service panel is activated, then the interfaceof the selector lever at the electronic control unit is interrupted.This interruption continues as long as the service panel is activated.It is, however, also possible, in order to avoid a conflict of control,not to activate the service panel until the control unit of thetransmission signals a corresponding failure.

The service panel possesses, advantageously, the necessary switchingfunctions for the gear shifting, these functions being on/off, neutral,forwards, reverse, clutch in, clutch out, shift up, and shift down. Withthe aid of such a service panel, all available gears can be shiftedthrough, even though this requires increased attention on the part ofthe driver. By this means, it becomes possible to continue travel evento a distant service station or to complete a homeward travel out of aforeign country.

There exist, fundamentally, two possibilities for connecting thetransmission control unit, which is integral with the transmission, tocontrol units of other systems of the vehicle. This is accomplished by aseparate, transmission-specific CAN-bus, which is to be provided inaddition to the vehicle-specific CAN-bus. Another way of accomplishingthe same thing is by a single, common, vehicle-specific CAN-bus, whichcoacts with a central electronic control unit. If only thetransmission-specific CAN-bus fails, the transmission control unit canbe regulated by the said service panel and the shifting will operate inits normal automatic manner. However, if the vehicle-specific CAN-busdrops out, then the shifting can be made only manually by means of theservice panel. For this purpose, the service panel possesses a number ofshifting functions, which the driver can activate. In doing this, thedriver makes use of, in the normal way, the information of a displayapparatus which will show the state of the shift in the transmission,along with the engine RPM and a speedometer.

The service panel can be continually connected with the transmissioncontrol unit. In order to assure the panel's availability and capabilityto function in case of an emergency, it is advantageous, to connect thisin a releasable manner with the said control unit. If this is done, thenin a normal situation, the service panel can be removed and protectivelyguarded in a safe place in the vehicle and made use of only in a case ofneed. In an advantageous manner, the service panel should be protectedagainst dust and dampness by sealing in a foil. Storage would bepreferred with the maintenance materials or the emergency tools of thevehicle.

So that the connection for the service panel can be checked by a regulardiagnostic examination, it is advantageous to provide the service panelwith a removable adapter, as long as the service panel is not included.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages are to be found in the following description with theaid of the drawing. In the drawing, examples of embodiments of theinvention are presented. The description and the claims contain manyfeatures in combination. The expert can, however, examine the featuresindividually and combine them to advantageous further combinations.There is shown in:

FIG. 1 a schematic construction of an emergency driving device in accordwith the invention; and

FIG. 2 a variant of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The emergency driving device 1 for an automatically controlledtransmission, encompasses essentially an electronic transmission controlunit 2 and an auxiliary service panel 13, which, over a signal line 24is connected to the control unit 2. This control, in accord with FIG. 1,first; is connected by means of a transmission-specific CAN-bus 8 to acontrol unit 6. Control unit 6, second, is connected through signallines with a selector lever 11 and a program switch 12. Anothervehicle-specific CAN-bus 7 connects the control unit 2 to an electroniccontrol unit 3 for a drive machine, which is not described in anyfurther detail, a control unit 4 for service brakes, which are notdescribed in any further detail, and a control unit 5 for a retardingbraking system. The control units 2, 3, 4, 5, 6 exchange data for theregulation of those systems assigned to said controls through theCAN-buses 7 and 8. The control units 2, 3, 4, 5, 6 further possessinputs 9 for regulation and control parameters and outputs 10 toactuators or the like.

Should the transmission-specific CAN-bus 8, or one of its interfaces, orthe signal lines 26 or selection lever 11 fail, then the control unit 2can be activated by the service panel 13. In the case of an activatedservice panel 13, the gear shifting signals through the interface of theCAN-bus 8 at the control unit 2 are blocked, so that only the controlwhich is generated through the service panel 13 is in force. The servicepanel 13 possesses a switch action for activating and deactivating(on/off), a switch function 15 for control of the neutral gear position,switch positions 16 and 17 for forward and reverse travel, switchfunctions 20, 21 for, respectively, shifting up one gear, shifting downone gear. In addition to these are switching positions 18 and 19, forthe opening and closing of a (not shown) main clutch. The current shiftposition of the transmission is shown on a display device 29 by a signalline 25.

Should the CAN-bus 7, or its interface to the control unit 2 drop out,the driver can shift the transmission by means of the service panel 13in the manner of a normal shift transmission. The torque and the engineRPM influence during shifting is regulated by the driver with the gaspedal. Upon the activation of the buttons 20 or 21, first the mainclutch is opened and the gear is released. Upon shifting up, the driverwaits just so long, until the engine RPM corresponds to the desired gearand the speed of the vehicle being represented on the speedometer 31.The engine RPM is shown by a speed of rotation meter 30, which isconnected by means of a signal line 28 with the control unit 3 for theengine. When the desired RPM of the engine is reached, and the driverreleases the currently activated button, then the desired gear is shiftsin and the main clutch closes. Upon shifting down, the engine RPM andthe corresponding travel speed are matched to the desired gear ratiostage, as the engine is accelerated by increasing the feed of fuel.

The embodiment in accord with FIG. 2, differs from the embodimentdepicted on FIG. 1, chiefly in that the transmission-specific CAN-bus isomitted and all control units 2, 3, 4, 5, 6 are bundled together over acommon CAN-bus 7. The control unit 6 takes over, as the central controlunit, the duties of a coordinating function. In case of a disturbance ofthe CAN-bus 7, the service panel 13 can regulate the control unit 2, asa normal shifting transmission. The engine RPM meter 30, in this case,is connected by a signal line 27 with the control unit 6.

The embodiment in accord with FIG. 2 shows further, a plug 22, so thatthe service panel 13 can be separated from the transmission control unit2. The service panel 13 can then be protected in a sealed foil in a safeplace on the vehicle, for example with the maintenance equipment or withthe emergency tools. If the service panel 13 is not connected, then anadapter 23 is connected with plug 22. Thereby, upon a diagnosis of theelectronic system, the functional capability of the connection line andthe connection itself can be tested, so that in case of emergency, theywill be found to be functional. The transmission control unit 2,advantageously, is installed directly on the transmission or isintegrated into the hydraulic or pneumatic control of the transmission.Thereby, a failure prone connection between the electronic and thehydraulic/pneumatic control elements is avoided.

In the case of the conventional emergency shifting concepts, i.e.emergency driving methods up to this time, the normal functionality inthe control equipment inclusive of the fault-reactions is not made useof in its full scope. In accord with the invention, the full scope offunctionality of the control equipment is made use of and only in thecase of the failure of interfaces, are substitute functions employed.

Reference Numbers

1 emergency driving device

2 control unit (transmission)

3 control unit (motor)

4 control unit (service brakes)

5 control unit (retarder brakes)

6 control unit (program/lever)

7 can-bus (FIGS. 1, 2)

8 can-bus (FIG. 1)

9 input (I)

10 output (O)

11 selector lever (gear shift lever)

12 program switch

13 service panel

14 on/off button

15 neutral gear button

16 forward button

17 reverse button

18 clutch open

19 clutch closed

20 one up gear

21 one down gear

22 disconnect plug (FIG. 2)

23 adaptor (for test without 13)

24 connecting signal line

25 connecting signal line

26 connecting signal line

27 connecting signal line

28 connecting signal line

29 display of current gear

30 engine rpm indicator

31 speedometer

What is claimed is:
 1. An emergency driving device (1) for a motorvehicle with an automatic shift transmission comprising: an electroniccontrol unit (2) integrally located in the transmission is connected viaat least one CAN-bus (7, 8) to additional control units (3, 4 5, 6) andto at least one selector lever (11) for exchanging measurement andtransmission regulation data therewith, and an auxiliary electronicservice panel (13) having a plurality of switching functions isconnected to the electronic control unit to provide transmission controlcomprising the positions of; on/off (14), neutral (15), forward (16),reverse (17), clutch open (18), clutch closed (19) and shift up one (20)and shift down one (21).
 2. The emergency driving device (1) for a motorvehicle according to claim 1, wherein the auxiliary electronic servicepanel (13) is releasably connectable to the electronic control unit (2)by a plug (22), to which during normal operation, an adapter (23) isaffixed to diagnosis the connection between the auxiliary electronicservice panel (13) and the electronic control unit (2).
 3. The emergencydriving device (1) for a motor vehicle according to claim 1, wherein thecontrol unit (2) which is integrated in the transmission is connected bymeans of a vehicle-specific CAN-bus, (7) having a first control unit (3)for a drive element, a second control unit (4) for a service brakingsystem and a third control unit (5) for a retarding brake system, thecontrol unit (2) is further connected by an exclusive CAN-bus (8) to afourth control unit (6) of the selector lever (11) for choosing one of agear stage and a switch (12) for the operational modus of thetransmission.
 4. The emergency driving device (1) for motor vehiclesaccording to claim 1, wherein the control unit (6) for the selectorlever (11), the control unit (3) for the drive machine, the control unit(4) for the service brake system and the control unit (5) for theretarder brake system, are connected by a common CAN-bus (8) with thetransmission control unit (2).
 5. The emergency driving device (1) formotor vehicles according to claim 1, wherein a connection between theservice panel (13) and the electronic control unit is activated, as soonas the transmission control unit (2) determines a fault in the CAN-bus(7, 8).
 6. The emergency driving device (1) for motor vehicles accordingto claim 1, wherein the transmission control unit (2) interrupts signallines (6, 8) between the selector lever (11) and the said control unit(2), as soon as the service panel (13) is activated.